Hummer 2006 H3 Owner's Manual page 314

Passenger's Side Shown
7. Locate the vertical headlamp aiming screws, which
are under the hood near each headlamp assembly.
The adjustment screw can be turned with an
®
E8 Torx socket or T15 Torx
5-48
®
screwdriver.
8. Turn the vertical aiming screw until the headlamp
beam is aimed to the horizontal tape line. If you turn
it clockwise, it will raise the beam and if you turn it
counterclockwise, it will lower the beam.
The top edge of the cut-off should be positioned at
the bottom edge of the horizontal tape line.
9. Repeat Steps 7 and 8 for the opposite headlamp.